The field of the invention is egg cartons and the invention relates more specifically to egg cartons of the type fabricated from a foamed plastic or from paper pulp.
Cartons for holding eggs have been in a gradual state of improvement and evolution for many years. The cardboard box with a cardboard grid insert has been replaced with a molded paper pulp carton, which in turn has been largely, but not entirely, replaced by molded foamed plastic cartons. Such molded plastic cartons typically are made from foamed polystyrene and have egg-shaped depressions in the lower part of the carton. These depressions hold and cushion the eggs, and help reduce breakage during filling, shipping, and handling of the cartons.
A major disadvantage of most molded foamed plastic cartons is their inability to hold eggs of different sizes and shapes. Eggs are graded according to size, based upon the weight of the egg. Two eggs which weigh the same, however, can have substantially different shapes. One may be practically spherical, whereas the other may be highly elongated. These egg shapes tend to vary throughout the year, and it is impractical to stock and/or manufacture enough different molded foamed plastic cartons to securely hold the various shapes of eggs. Furthermore, different egg cartons must be molded for different sizes of eggs. For instance, a molded foamed plastic egg carton made for extra large eggs typically should not be used for large eggs without undue breakage during handling. Still further, eggs larger than "extra large" (jumbo) or eggs smaller than medium (small or pee wee) are not commonly sold in supermarkets because they cannot be conveniently adapted to the standard egg carton. For instance, it is impractical or impossible to insert one dozen jumbo eggs in an egg carton having a standard exterior dimension. If the egg carton does not have the standard exterior dimension, it will not fit in the normal shipping cartons, and thus cannot be economically handled. Conversely, one dozen small or pee wee eggs does not provide a sufficient weight of eggs to make a practical purchase. It would be advantageous to provide an egg carton which has the capability of holding more than one dozen of such small eggs. Conversely, it would be advantageous to provide an egg carton which could hold less than one dozen, such as ten, jumbo eggs. It would likewise be useful to provide egg cartons having the capability of securely holding elongated and almost spheroidal eggs of the same size or weight class.